The Effects of Latent Print Processing on Ballpoint Pen Inks

Latent print (LP) processing and subsequent examination of twenty-five ballpoint inks revealed significant changes in ultraviolet fluorescence (UVF), infrared luminescence (IRL) and infrared reflectance (IRR) that could result in the incorrect identification or elimination of an ink when addressing alterations, multiple authorship, or comparing a specific pen to questioned entries. The inks were processed with three common ninhydrin solutions, then processed with physical developer. Subsequent examination revealed frequent dequenching of UVF and IRL, as well as changes to IRR properties and visible color. Thin-Layer Chromatography (TLC) plates were run for fifteen inks, but did not reveal any significant changes to inks after LP processing. Sometimes there were little or no visible signs of LP processing, suggesting police departments should notify examiners if they process documents for LPs prior to submission.